Many devices, e.g., portable electronic devices such as cell phones and media players, include housing walls formed from structurally strong and stiff materials such as stainless steel. The strength provided by materials such a stainless steel enables housing walls to protect internal components of portable electronic devices, and enhances the durability of such devices.
In some applications, while stainless steel provides desirable strength characteristics for housing walls, the stainless steel may not provide acceptable cosmetic characteristics. For example, a stainless steel surface is often relatively easy to scratch, and a scratched stainless steel surface may be unappealing. Although anodizing processes may be used on some metals in order to effectively provide a scratch-resistant surface, stainless steel may not be anodized, as rust forms on stainless steel due to oxidation. Hence, for applications in which cosmetic appeal is a relatively important feature, the use of stainless steel may be undesirable.
Metals such as aluminum may be anodized to prevent scratching. That is, the surface of some metals, such as aluminum, may be anodized such that the surface becomes substantially scratch-resistant. However, aluminum is relatively weak structurally. Hence, while an aluminum surface may be anodized to protect the surface from being scratched, the use of aluminum as a housing may be undesirable due to the lack of structural strength associated with aluminum.
Therefore, what is needed is a method and an apparatus which enables a relatively strong, cosmetically-appealing housing wall to be created.